Controlling Rats and
Mice In Swine Facilities
Originally published as PIH-107.
Authors:
Robert M. Timm, University of California
Rex E. Marsh, University of California - Davis
Scott E. Hygnstrom, University of Nebraska - Lincoln
Robert M. Corrigan, Richmond, Indiana
Reviewers
Bob and Diane Bell, Camden, Arkansas
Bob and Diane Bell, Camden, Arkansas
Mike and Debbie Nichols, Oakfield, Tennessee
G. K. Yarrow, Clemson University
Rats and mice can be a major economic threat around swine facilities. They consume and contaminate feed
and cause feed losses through the gnawing of holes in feed sacks and wooden bins. They also have been
implicated in maintaining or spreading diseases.
House mice (Mus musculus), Norway rats (Rattus norvegicus), and roof rats (Rattus rattus) as a group are
considered the most troublesome and economically important rodents in the United States. These nonnative
“commensal” rodents live under a variety of urban and rural conditions. They often thrive in and around
farms and rural homes, and sometimes inhabit open fields and agricultural crops.
Norway rats will undermine building foundations and concrete slabs. Roof rats and house mice, in addition
to Norway rats, are particularly destructive to building insulation. Most common types of insulation, including rigid foam and fiberglass batt, are susceptible to rodent damage. A rodent infestation can cause thousands of dollars in damage in a matter of months. Additionally, rodents frequently gnaw on electrical wiring
causing equipment malfunctions, power outages, and fires as a result of short circuits. Norway rats and
house mice are found in all of the contiguous 48 states, although the Norway rat may be absent from some
relatively large geographic areas in the West. The roof rat primarily occupies coastal areas of Washington,
Oregon, and California, as well as a larger area encompassing the coastal states from Texas to Maryland.
Rodents and Swine Diseases
Rodents and other wildlife can play an important role in the transmission of swine diseases, although the
occurrence of such diseases in rodents and their contribution to disease problems on hog farms is not well
documented.
Table 1 lists swine diseases that rats and mice may harbor or disseminate. Rodents, like other wild animals,
insects, and people, are capable of carrying diseases into a swine facility. Rodents can spread or accelerate
the spread of diseases from contaminated areas to uncontaminated areas via their droppings, feet, fur, urine,
saliva, or blood. As an example, Norway rats may travel through infected feces of sick pigs and then
contaminate feed or water several hundred feet away. Rodents, if eaten by swine, also can directly transmit
PAGE PIG 06-01-01
Table 1. Diseases of swine in North America
that rodents may harbor or transmit.
diseases.
Additionally, rodents around farm buildings are a food
source that can attract predatory animals such as
foxes, coyotes, raccoons, skunks, or stray dogs and
cats, that in turn may contribute to disease problems.
An effective disease barrier system cannot be achieved
or maintained without good rodent control.
Recognizing Rodent Infestations
Disease
Agent
Rodents implicated
Bordetellosis
Encephalomyocarditis
Leptospirosis
Pseudorabies
Salmonellosis
Swine Dysentery
Swine Erysipelas
Toxoplasmosis
Trichinosis
bacteria
virus
bacteria
virus
bacteria
bacteria
bacteria
protozoan
nematode
rats
rats, mice
rats, mice
rats*
rats, mice
rats, mice
rats
various rodents
rats
Table
1. Diseases
of swine
in North
that
ro*Opinions
differ
on the significance
of rodents
as theAmerica
reservoir or
vector.
dents may harbor or transmit. *Opinions differ on the
Droppings, tracks, burrows, pathways, and fresh
significance of rodents at the reservoir or vector.
gnawings including damaged feed sacks, indicate areas
where rodents are active. Rodent nests, made from
fine shredded paper or other fibrous material, are often found in sheltered locations. Insulated walls and
ceilings are common nesting locations for rodents, especially mice. Rats also use these areas as well as burrow into the ground inside and outside of swine buildings. When present in relatively high numbers, rats
and mice occasionally can be seen during daylight hours, but they are most active at night, particularly just
after dusk. Thus, conducting an inspection of the premises at nightfall may assist in identifying the location,
distribution, and severity of a rodent infestation.
Rat and Mouse Facts
House mice are small, brownish to grayish rodents with relatively large ears and small black eyes. They
weigh about 1/2 oz. An adult is about 5 1/2 in. to 7 1/2 in. long including the 3- to 4-in. tail. Norway rats are
large, robust animals whose fur color ranges from reddish to grayish brown on the back and sides and gray
to yellow-white underneath. They are about 13 in. to 18 in. long including the 6- to 8 1/2-in. tail. Average
weight is about 11 oz, and few individuals exceed 1 lb. In comparison, the roof rat is a smaller, sleeker rat
usually colored blackish to gray, with a gray to whitish underside. A roof rat, in contrast to the Norway rat,
has a tail longer than its head and body combined, and a more pointed snout. Also, its eyes and ears are
relatively larger than the Norway’s.
Although commensal rodents often feed on cereal grains, they will eat many kinds of food including garbage,
insects, meat, and even manure. House mice are sporadic feeders, nibbling bits of food here and there, but
often causing more economic loss from gnawed feed sacks, contaminated feed, or from transmitted disease
than from actual food consumed. Rats tend to get their daily food at one or two locations. They require 1/2
oz to 1 oz of water daily (unless feeding on moist or succulent foods), but house mice can survive for long
periods without free water.
Rats and mice have keen senses of taste, hearing, smell, and touch. Roof rats are excellent climbers and
often live on the second story of farm buildings if food is available. House mice and Norway rats will climb
to reach food or shelter, and all three species can climb any rough vertical surface. They can run horizontally
along wire cables or ropes and can jump up 36 in. (12 in. for house mice). Rats can squeeze through
openings slightly larger than 1/2 in. across, while house mice require an opening slightly larger than 1/4 in.
These rodents have impressive capacities for reproduction, which makes it necessary to control them early
and diligently, before populations reach levels that cause significant damage. For example, in a single year
a female house mouse may have 5 to 10 litters of usually 5 or 6 young each. Young are born 19 to 21 days
after mating, and they reach reproductive maturity in 6 to 10 weeks. The life span of a mouse is usually 9
to 12 months. Norway and roof rats are only slightly less fecund, with individuals typically living 9 to 12
months but sometimes longer. Where both rats and house mice exist on the same premises, rats may
exclude house mice from their main areas of activity. Following the control of rats, mice may flourish.
Rodent Control
For effective control, we recommended an integrated pest management (IPM) approach that incorporates
the timely use of a variety of cost-effective control methods, including: (1) sanitation, (2) rodent-proof
construction, and (3) population reduction. The first two are preventive measures. When an
infestation already exists, population reduction is typically needed. Reduction techniques include trapping,
PAGE PIG 04-04-04
Table 2.
Concrete
Galvanized
Brick
Hardware c
Aluminum
Table 1. Diseases of swine in North America
that rodents may harbor or transmit.
toxic baits, and fumigation. Another
Disease component Agent
Rodents
implicated
important
of an effective
IPM
Bordetellosis
bacteria
rats
program is pest population monitoring. Records
Encephalomyocarditis
virus
of trapping
success and
measuresrats,
of mice
rodent acLeptospirosis
bacteria
rats, mice
tivity will help to determine the need for
Pseudorabies
virus
rats*
additional
control efforts.
Salmonellosis
bacteria
rats, mice
Swine Dysentery
bacteria
rats, mice
Table 2. Recommended materials for rodent-proofing.
Concrete
Minimum thickness of 2 in. if reinforced,
or 3 3/4 in. if not reinforced.
Galvanized sheet metal
24 gauge or heavier. Perforated sheet
metal grills should be 14 gauge.
Brick
3 3/4 in. thick with joints filled with mortar.
Hardware cloth (wire mesh)
19 gauge 1/2 x 1/2 -in. mesh to exclude
Sanitation.
Although good
sanitation
Swine Erysipelas
bacteria
rats will seldom
rats; 24 gauge 1/4 x 1/4 -in. mesh to
Toxoplasmosis
protozoan will various
eliminate
rodents, it certainly
aid inrodents
controlexclude mice.
rats
lingTrichinosis
them. Conversely,nematode
poor sanitation
is sure
Aluminum
22 gauge for frames and flashing
to*Opinions
attractdiffer
rodents
and permit
them
thrive
in
on the significance
of rodents
as theto
reservoir
or vector.
20 gauge for kick plates
greater abundance. The continual presence of a
18 gauge for guards.
sizable rodent population suggests that too little
Table 2. Recommended materials for rodent-proofing.
attention is being given to the proper maintenance of the facilities. Although inadequate sanitation contributes to more serious rodent problems, rodent
infestation (particularly house mice) does not necessarily mean that sanitation is inadequate.
On farms where feed grains are handled and stored, or where livestock are housed and fed, it is generally
impossible to exclude rodents from all available food. In such situations, removing shelter that rodents can
use for hiding, resting, and nesting is valuable in control. Regular removal of debris and control of weeds
around structures will reduce the amount of shelter available to rodents. Additionally, a clean, 3-ft weed-free
perimeter around structures may make rodents feel more “exposed” and permit easier detection of rodent
activity.
It is almost impossible to eliminate house mice through sanitation alone, particularly on farms, because they
can survive in very small areas with limited amounts of food and shelter. Most buildings in which livestock
feed is stored, handled, or used, will support a thriving population of house mice if the building is not
mouse-proofed. Store feeds in rodent-proof buildings, rooms, or containers whenever possible. Stack
sacked feed on pallets with adequate space left around and under stored articles. This will allow easy
inspection for evidence of rodent activity, and it will facilitate placement of traps or baits.
Rodent-proof construction. A lasting form of rodent control is to “build them out” by eliminating all openings through which they can enter a structure. Where feasible, rodent-proof all places where feed is stored,
processed, or used.
The paired front (incisor) teeth of rats and mice curve slightly inward, making it difficult for them to gnaw
flat, hard surfaces. However, when given a rough surface or an edge, they can quickly gnaw into all but the
hardest of materials. By gnawing, rats can gain entry through any opening greater than 1/2 in. across. Mice
can enter a building through any opening larger than 1/4 in. across. To prevent rodent entry, seal all such
holes with durable materials. Steel wool, packed tightly into openings, is a good temporary plug. To close
openings or protect other areas subject to gnawing, use materials such as those listed in Table 2. Plastic
sheeting or screen, wood, rubber, or other gnawable materials are not adequate for sealing openings used
by rodents. Close openings around augers, pipes, and wires where they enter structures with mortar, masonry, or metal collars. A common entry point for mice into buildings is the unprotected end of corrugated
or ribbed metal siding. If not blocked with metal or mortar, these openings provide access into wall spaces
and the building interior. Rubber or vinyl weather stops are quickly gnawed through. Design or modify
buildings so that metal siding butts directly against the sill plate or foundation.
Doors, windows, and screens should fit tightly. It might be necessary to cover the edges with metal to
prevent gnawing. Depending on the age and type of construction, it might not be feasible to rodent-proof
the building. In such instances, more attention must be given to other techniques of rodent control.
Rats (and other wildlife) can be discouraged from burrowing near foundations by laying a strip of coarse
gravel around their perimeter. Gravel should be at least 1 in. in diameter and laid in a band at least 2 ft
wide and 1/2 ft deep. Rat burrowing under concrete slabs or foundation walls also can be prevented by
installing a buried curtain of 1/2-in. hardware cloth, extending downward 12 in. to 18 in. with a lip at the
bottom extending outward 12 in. (Figure 1).
PAGE PIG 04-04-04
Trapping. Trapping is an effective way to control rodents. House mice
are relatively easy to trap, but trapping rats requires more skill and
labor. Try trapping first where rodents are few; severe infestations will
likely require additional measures. Trapping has several advantages:
(1) it does not rely on potentially hazardous rodenticides; (2) success
is easily visible; and (3) it allows for disposal of the rodent carcasses,
thereby eliminating dead animal odors which may occur when poisoning is done within buildings.
The simple, inexpensive wood-based snap trap is effective. Snap traps
are available through farm supply or hardware stores and from pest
control suppliers. Bait the traps with a mixture of peanut butter and
rolled oats or with a small piece of bacon, lunch meat, or cheese tied
securely to the trigger. Set them so that the trigger is sensitive and will
spring easily. You can reduce the chance of creating trap-shy rodents
by leaving traps baited but unset until the bait has been taken at least
once.
1. A curtain wall of hardware
Figure 1.Figure
A curtain
wall of hardware cloth can
cloth can prevent rats from burrowing
®
Multiple-capture live traps for mice, such as the Victor Tin Cat and the
prevent rats
from
burrowing
concrete slabs or
under concrete slabs orunder
foundation
Ketch-All® are effective and will save service time. They, too, are availfoundation walls.
walls.
able in some hardware and feed stores as well as from pest control
suppliers.
Set traps close to walls, behind objects, in dark corners, and in places where rodent activity is evident.
|Tracking patches of talc or flour can be used to determine where rodents are active. Traps may be placed on
ledges or on top of pallets of stored materials if mice or rats are active there. Where possible, place snap
traps so that rodents will pass directly over the trigger as they follow their natural course of travel, usually
close to a wall (Figure 2). Some snap traps, such as the Victor® Professional, have enlarged triggers that
catch rats or mice when they travel over them. When set correctly, it is possible to catch rodents that are not
even attracted to baits.
Use enough traps to make the campaign short and decisive. Mice seldom venture far from their shelter and
food supply, so space snap traps no more than 10 ft apart in areas where mice are active. When using snap
traps, it may be best to trap intensively for 2 to 3 weeks and then “rest” for a couple weeks before resuming
efforts. This may save some labor costs and helps prevent rodents from becoming “trap-shy.” Place multiple
catch traps in areas where mice are persistent and where mice are gaining access to the building (for example,
on both sides of doorways). Maintain accurate records to determine the effectiveness of trap placement and
overall trapping success. Multiple catch traps should be checked frequently to remove captured mice. Glue
boards are another type of rodent trap. They catch and hold rodents that attempt to cross them in much the
same way flypaper catches flies. Glue boards are available where rodent baits and traps are sold, or can be
ordered from
Figure 3. A rodent bait box attached to the top of a
pest control suppen dividing wall in a swine indoor facility. When
pliers. Place glue
used in such locations, bait boxes must be securely
boards along
fastened and out of pigs’ reach.
walls where
rodents travel.
Do not use them
where children,
Table 1. Diseases of swine in North America
pets, or desirthat rodents may harbor or transmit.
able wildlife have
Disease
Agent
Rodents implicated
access to them,
Bordetellosis
bacteria
rats
because they
Encephalomyocarditis
virus
rats, mice
stick tenaciously
Leptospirosis
bacteria
rats, mice
to any object
Pseudorabies
virus
rats*
coming in conSalmonellosis
bacteria
rats, mice
tact with them.
Swine Dysentery
bacteria
rats, mice
lose
l of hardwareGlue
clothboards
can
Swine Erysipelas
bacteria
rats
owing under concrete
slabs or
their effectiveFigure 2. Right and wrong placement of snap traps.
Toxoplasmosis
protozoan
Figure 2. Right
and wrong placement
of snap various
traps. rodents
Trichinosis
PAGE nematode
rats
PIG 04-04-04
*Opinions differ on the significance of rodents as the reservoir or vector.
Table 3. Non-anticoagulant rodenticides and some of their useful
characteristics for controlling rats and mice in swine facilities.
Percent
ness in dusty
a.i.*
Mode of
Time to
Bait
Bait
Human
Swine
areas unless
Common name
Chemical namein
food bait
action
death
acceptance shyness
hazard
hazard
covered, and
Bromethalin
N -methyl-2,4-dinitro0.01
CNS**
2-4 days
good
none
moderate unknown
temperature
(Assault®,
N -(2,4,6-tribromodepression
reported
Vengeance®
phenyl)-6-trifluoroand paralysis
extremes also
methyl) benzenamine
may affect their
Cholecalciferol
9,10-Seocholesta-5,7,
0.075
Mobilizes
3-4 days
fair-good
none
lowunknown
tackiness. To
(Quintox®,
10(19)-trein-3 betaol
calcium
reported
moderate
protect the glue Rampage®)
resulting in
death from
board from
hypercalcemia
dust and from
Zinc phosphide
zinc phosphide
1.0 - 2.0
Phosphine gas
1/2-20 hrs. fair
moderate- moderate moderate
disturbance,
(Ridall Zinc®, ZP®)
enters circulatory
high
system; heart
place it inside a
paralysis, gastrobait station, or
intestinal and
liver damage
install a special
*
active
ingredient
**Central
Nervous
System
Table
3.
Non-anticoagulant
rodenticides
and
some of their useful characteristics for controlling rats
protective
and
mice
in
swine
facilities.
*Active ingredient. **Central Nervous System.
cover deTable 4. Anticoagulant rodenticides for controlling rats and mice in swine facilities.
signed to fit
over the glue board. The user can place the glue board in a cardboard or wooden box the size of a shoe box, Percent active
ingredient used
with a hole cut inCommon
each end
to enter.
name for the rodents
Chemical
name This can be an aid in disposal of carcasses, although rats in food bait
may be wary of the box and may not enter for several days. Glue boards are more effective for capturing
3-{3-[4'-bromo(1,1'-biphenyl)-4-yl]-1,2,3,4-tetrahydro-1-naphthalenyl}-4-hydroxy-2H-1-benzopyran-2-one 0.005
mice than rats. Brodifacoum (Havoc® Talon®)
Bromadiolone (Maki®, Contrac®) 3-{3-[4'-bromo(1,1'-biphenyl)-4-yl]-3-hydroxy-1-phenylpropyl}-4-hydroxy-2H-1-benzopyran-2-one
0.005
Chlorophacinone (RoZol®)
2-{(p-chlorophenyl)phenylacetyl}-1,3-indandione
0.005
Using toxic baits Difethialone
(rodenticides).
Rodenticides
are pesticides designed to kill rodents. Both anticoagulant
(Generation®)
[(bromo-4'-[biphenyl-1-1']-yl-4)3-tetrahydro-1,2,3,4-napthyl-1]3-hydroxy-4,2H-1
benzo-thiopyran-2-one
0.0025
Diphacinone
(Ramik®)
2-diphenylacetyl-1,3-indandione
and non-anticoagulant
rodenticides
are available.
Although a wide variety of ready-to-use baits are available,0.005
Pindone (Pival®)
2-pivalyl-1,3-indandione
0.025
some experts in rodent
control prefer to 3-(α-acetonylbenzyl)-4-hydroxycoumarin
mix their own baits using rodenticide concentrates. In most situa- 0.025
Warfarin
tions, however, ready-to-use commercial baits are preferred because they have proven efficacy and do not
require that the applicator handle the concentrated toxicant, which may be more hazardous.
Some non-anticoagulant rodenticides (Table 3) will give a quicker knockdown of a rodent population than
anticoagulants, as they are effective with a single feeding and are relatively rapid in action. They may be
preferred where rodents are abundant or where it is difficult to get them to accept a bait for several days
in succession (as is necessary with some anticoagulants) because of competing food items.
The most common non-anticoagulant rodenticides are bromethalin and cholecalciferol. Bromethalin killsrodents by disrupting the energy production within thecells of the body. Eventually, this results in a decrease
in nerve impulses, paralysis, and death. A single dose of bait is usually lethal within 2 to 4 days. Rodents
stop feeding on bromethalin baits after they have consumed a lethal dose. Thus, only relatively small
amounts of this bait need to be available.
Cholecalciferol is actually vitamin D3. In massive doses this compound is toxic—especially to rodents, and
because of their small size, rodents succumb to relatively small amounts. Cholecalciferol will act as a singledose poison if a sufficient amount is consumed by a rodent in one feeding, but it will act as a multiple-dose
poison if consumed in lesser amounts over several days. Zinc phosphide has been used as a rodenticide for
many years. It is a blackish powder with a distinctive garlic-like odor that is said to be attractive to rats and
mice, but is generally unattractive to humans and pets. It is available in ready-to-use commercial baits.
Use of zinc phosphide has declined because of the relatively more effective new generation anticoagulant
and non-anticoagulant rodenticides. However, it is still an effective and useful material, and it can provide
an economical and quick knock-down of a rodent population. Because “bait shyness” may develop following a sublethal ingestion of zinc phosphide, it is best not to use this active ingredient more than twice per
year at a given location, and preferably only once. “Prebaiting” with untreated bait for several days before
a zinc phosphide rodenticide is offered will increase bait acceptance, thereby increasing control success.
Because the modes of action of non-anticoagulants are completely different from that of the anticoagulants,
they are effective against anticoagulant-resistant rodents. Non-anticoagulant rodenticides can be hazardous
to humans, pets, or livestock if accidentally ingested, because they are more rapid in action and because
first aid treatments are often less effective than with anticoagulants.
Anticoagulant rodenticides (Table 4) comprise about 90% of all baits used for rodent control. Anticoagulants
cause death by internal bleeding, which occurs as the animal’s blood loses its clotting ability and capillaries
PAGE PIG 04-04-04
are destroyed. The active ingredients are used at very low levels, and bait shyness does not occur primarily because of their slow action. All anticoagulant rodenticides are relatively slow-acting and death usually
occurs 3 to 7 days following the ingestion of a lethal amount. Most anticoagulant baits cause death only
after they are eaten for several days. Brodifacoum, bromadiolone, and difethialone baits are exceptions, as
these rodenticides can cause death following a single feeding, although the rodent may continue to feed
for several days. All anticoagulants are considered to have good bait acceptance, low human hazard, and
moderate- to high- hazard if directly ingested by swine.
When multiple-dose anticoagulant rodenticides are used, bait must be available continuously until all
rodents stop feeding. This usually takes at least 2 weeks. Complete elimination of rodents is often possible
with anticoagulant rodenticides. This is not usually achieved with non-anticoagulant rodenticides, and
hence the anticoagulants are often used as a follow-up to other types of control.
Occasionally populations of rodents have been known to develop that are resistant to certain anticoagulants.
This usually occurs following use of multiple-dose products continually for several years at one location.
However, resistant rodents can be controlled by using a singlefeeding anticoagulant (brodifacoum,
bromadiolone, or difethialone) or by using one of the non-anticoagulants.
Bait selection and placement. Rodent baits are available in several forms. Grain baits in a loose meal or
pelleted form are available in small plastic, cellophane, or paper packets. These sealed “place packs” keep
bait fresh and permit easy placement of the baits into burrows, walls, or other locations. Rodents gnaw into
the packets to feed on the bait. When baiting, check that packets have not been pushed out of burrows by
rats, as this may expose bait to non-target animals.
Anticoagulant baits formulated into paraffin or wax blocks are useful, especially in damp locations, where
loose grain baits would spoil quickly. As with place packs, avoid placing them where they could be reached
and fed on by pigs. Where ample feed is available to rodents, control can be improved by using baits
prepared of highly-preferred foods. A particularly good bait material for house mice is canary grass seed.
In many situations, mice prefer such bait to hog feed or other cereal grains, if it is made readily available to
them. Likewise, those anticoagulant baits that are lethal in a single feeding can be more effective in these
situations.
Table 3. Non-anticoagulant rodenticides and some of their useful
characteristics
forof
controlling
rats content
and mice in
swine
facilities.
Water or
food items
high water
are
often
attractive to rodents at sites where water is scarce or
Percent
absent. Some anticoagulant concentrates
can be dissolved in water to make a liquid bait. Even though mice
a.i.*
Mode of
Time to
Bait
Bait
Human
Swine
require little
water
they willfood
quickly
accept available
baits. When
Common
name to survive,
Chemical namein
bait
action
death water
acceptance
shyness water
hazardsources
hazardcan be
reducedBromethalin
or eliminated,N liquid
baits
will
provide
excellent
control
of
rats.
Liquid
baits
also
can
supplement
-methyl-2,4-dinitro0.01
CNS**
2-4 days
good
none
moderate unknown
cereal baits,
resulting
in
better
control.
(Assault®,
N -(2,4,6-tribromodepression
reported
Vengeance®
phenyl)-6-trifluoromethyl) benzenamine
and paralysis
Proper placement of baits and the distance between them is very important. Baits must be located where
9,10-Seocholesta-5,7,
0.075
Mobilizes
days
fair-good
none
unknown
rodents Cholecalciferol
are living, as close
to their
possible and3-4closer
than their
normallowfood resources.
For
(Quintox®,
10(19)-trein-3
betaol shelter as is
calcium
reported
moderate
Rampage®)
resulting
in
house mice,
place baits no farther than 10 ft apart
(preferably
6 ft to 8 ft). Since rats will travel farther to feed,
death from
baits can be spaced 25 ft to 50 ft apart. Whenever
possible, however, place rat baits directly into, or very
hypercalcemia
close to, rat burrows.
Zinc phosphide
(Ridall Zinc®, ZP®)
zinc phosphide
1.0 - 2.0
Phosphine gas
1/2-20 hrs. fair
moderate- moderate moderate
enters circulatory
high
system;
heart holding ample toxic bait for nearby rodents. Bait
Bait boxes or stations provide a secluded feeding
area,
paralysis, gastroboxes protect the bait from weather and exclude
pets
and other non-target animals. They should be large
intestinal and
livertime
damage
enough to accommodate several rodents at one
and should have at least two rodent-sized openings
(1
* active ingredient
**Central Nervous System
1/2 in. for
mice, 2 1/2 in. for rats).
Place bait boxes next to walls (with the openings close to the wall), or near
burrows and in other places where rodents are active. Clearly label all bait boxes with “Rodent Bait—Do Not
Table 4. Anticoagulant rodenticides for controlling rats and mice in swine facilities.
Common name
Chemical name
Percent active
ingredient used
in food bait
Brodifacoum (Havoc® Talon®)
Bromadiolone (Maki®, Contrac®)
Chlorophacinone (RoZol®)
Difethialone (Generation®)
Diphacinone (Ramik®)
Pindone (Pival®)
Warfarin
3-{3-[4'-bromo(1,1'-biphenyl)-4-yl]-1,2,3,4-tetrahydro-1-naphthalenyl}-4-hydroxy-2H-1-benzopyran-2-one
3-{3-[4'-bromo(1,1'-biphenyl)-4-yl]-3-hydroxy-1-phenylpropyl}-4-hydroxy-2H-1-benzopyran-2-one
2-{(p-chlorophenyl)phenylacetyl}-1,3-indandione
[(bromo-4'-[biphenyl-1-1']-yl-4)3-tetrahydro-1,2,3,4-napthyl-1]3-hydroxy-4,2H-1 benzo-thiopyran-2-one
2-diphenylacetyl-1,3-indandione
2-pivalyl-1,3-indandione
3-(α-acetonylbenzyl)-4-hydroxycoumarin
0.005
0.005
0.005
0.0025
0.005
0.025
0.025
Table 4. Anticoagulant rodenticides for controlling rats and mice in swine facilities.
PAGE PIG 04-04-04
Fig
foundation walls.
Touch” or other appropriate warnings as a safety precaution. To
prevent bait boxes from being tipped over, fasten them to the floor
or wall (Figure 3). Secure the lids to prevent unwanted access to
the bait. Bait stations can be constructed from scrap lumber, or
they can be purchased from suppliers. Examples of commercially
available rat and mouse bait stations are shown in Figure 4. Some
of the newer, “tamper-resistant” bait stations available from pest
control supply distributors are more durable and will hold up inside swine housing structures better than light plastic or cardboard
stations.
Fumigants. Fumigants are commonly used to control Norway rats
in their burrows in outdoor situations. Compounds such as carbon
monoxide (gas cartridges) and aluminum phosphide have been
used to fumigate rat burrows. Fumigation of house mice is usually
limited to situations where they occur inside structures such as
grain bins or warehouses. Caution! Fumigants are highly toxic to
Figure 1. A curtain wall of hardware cloth can
humans and other animals. They must not be used in any situation
Figure 3. A rodent bait box attached to the
prevent rats from burrowing under concrete slabs or
top
of
penwrong
dividing
wall
in aofto
swine
indoor
Figure
A arodent
bait box
attached
the traps.
top
of a
Figure
2. 3.
Right
and
placement
snap
that mightfoundation
expose people
or
domestic
animals
to
the
gases.
Bewalls.
facility.wall
When
used in
suchfacility.
locations,
bait
in a swine
indoor
When
cause of inherent potential hazards with fumigants, only licensed pen dividing
must be bait
securely
and out
used inboxes
such locations,
boxesfastened
must be securely
structural pest control operators should use fumigants in any situaof pigs’ reach.
fastened
and
out
of
pigs’
reach.
tion involving buildings or other structural enclosures.
Maintaining control. Once “control” is achieved, some pork
producers tend to let their guard down and not pay much
attention to rodent control for a couple of months. Unfortunately, this habit leads to “undoing” all the work that it
took to control the rodents initially. Keep in mind that a few
rodents are likely to survive even the most thorough control
effort. Also, rodents from nearby fields or structures may
invade swine facilities
at any time. These rodents will multiply quickly if not kept in
check with an ongoing control program.
Therefore, it is important to establish permanent bait stations in farm buildings and around their perimeter. Fresh
anticoagulant bait in these stations will control invading
rodents before breeding populations become established.
Figu
in siz
appr
Table 1. Diseases of swine in North America
that rodents may harbor or transmit.
Disease
Agent
Rodents implicated
Bordetellosis
Encephalomyocarditis
Leptospirosis
Pseudorabies
Salmonellosis
Swine Dysentery
Swine Erysipelas
Toxoplasmosis
Trichinosis
bacteria
virus
bacteria
virus
bacteria
bacteria
bacteria
protozoan
nematode
rats
rats, mice
rats, mice
rats*
rats, mice
rats, mice
rats
various rodents
rats
*Opinions differ on the significance of rodents as the reservoir or vector.
Ta
Co
Ga
Bri
Ha
Alu
Figure 4. Commercially-available bait stations
Rodent control should be a regular and continual part of a
come in sizes for mice or rats, and include bait
Figure
4. Commercially-available
bait stations come
stations
approved as “tamper-resistant”
(right).
pork production
Take
hour or
each
Figure 3.operation.
A rodent bait
boxan
attached
to two
the top
of amonth,
in
sizes
for
mice
or
rats,
and
include
bait
stations
after control
beenwall
achieved,
checkfacility.
and refill
bait stapenhas
dividing
in a swinetoindoor
When
approved as “tamper-resistant” (right).
tions and inspect
facilities
for bait
fresh
rodent
Mark it on the calendar.
used in such
locations,
boxes
mustactivity.
be securely
fastened and out of pigs’ reach.
Safety precautions. Some general safety precautions should be followed in addition to those appearing on
product labels. Consider all rodenticides sufficiently toxic to cause death to pigs. Take care to keep baits out
of the reachTable
of domestic
animals
or non-target
wildlife; place baits where only rodents can access them.
1. Diseases
of swine
in North America
Table 2. Recommended materials for rodent-proofing.
Rodenticides
may
present
some
hazard
to predators or scavengers that feed on the carcasses of poisoned
that
rodents
may
harbor
or transmit.
Concrete
Minimum
thickness
of 2 in. if reinforced,
rodents. Remember
that hogs will
often feedRodents
on rodent
carcasses.
Therefore, pick up and
properly
dispose
Disease
Agent
implicated
3/4 in. if not reinforced.
or
3
of any rodent carcasses that result from the use of toxic baits. Handle rodent carcasses with rubber gloves,
Bordetellosis
bacteria
rats
long tongs, orEncephalomyocarditis
several layers of newspaper.
As
an added safetyGalvanized
precaution,
keep dogs or
cats confined or
sheet metal
24 gauge or heavier. Perforated sheet
virus
rats, mice
well-fed whileLeptospirosis
initial baiting operations
progress.
bacteria are in
rats,
mice
metal grills should be 14 gauge.
Pseudorabies
virus
rats*
Brick
3 3/4 in. thick with joints filled with mortar.
Label all bait Salmonellosis
containers and stations
clearly rats,
with
appropriate warnings,
and keep unused
bait in its original
bacteria
mice
1/2 outside
container. Store
bait
and concentrates
cabinet and post
appropriate
warnings
on the
of to exclude
Swine
Dysentery
bacteria in a locked
rats, mice
Hardware
cloth (wire mesh)
19 gauge
x 1/2 -in. mesh
Swine
Erysipelas
rats
cabinet doors.
If baits
are storedbacteria
with other chemicals,
be sure they are packaged in airtight
rats; 24containers
gauge 1/4 x 1/4to
-in. mesh to
Toxoplasmosis
protozoanodors
various
prevent absorption
of foreign chemical
that rodents
will reduce the baits’ acceptance by rodents.
Carefully
exclude mice.
Trichinosis
nematode
rats
follow label directions. Remove and destroy all uneaten bait at Aluminum
the end of the poisoning22program.
When
gauge for frames and flashing
using permanent
properly
dispose
of any
old, spoiled, or contaminated baits.
*Opinionsbait
differ stations,
on the significance
of rodents
as the reservoir
or vector.
20 gauge for kick plates
18 gauge for guards.
PAGE PIG 04-04-04
Sound and electronic devices. Although rodents are easily frightened by strange or unfamiliar noises,
they quickly grow accustomed to regularly repeated sounds and thus live in grain mills and factories with
high sound levels. Ultrasonic sounds—those above the range of human hearing—have very limited if any
use in rodent control because they are directional and do not penetrate behind objects. Also, they lose their
intensity quickly with distance. There is no good evidence that sound of any type will drive established mice
or rats from buildings.
Predators. Although cats, dogs, and other predators may kill rodents, they do not provide effective control
in most circumstances. It is common to find rodents living in very close association with dogs and cats.
Mice and rats may obtain much of their diet from the pet’s dish or from what pets spill.
Summary
1.
2.
3.
Eliminate or reduce the number of places rodents can use for shelter. Prevent clutter in and
around buildings, and keep stored feed in rodent-proof facilities. Where practical, make
structures rodent-proof. When rodents have no place to hide or nest, they cannot thrive.
If rodents or evidence of rodents are present, begin or increase control efforts. Use traps or
rodenticides to reduce their numbers. Place baits or traps in areas where rodents are active,
and maintain control efforts diligently until successful.
Once rodent numbers have been reduced, continue a regular program of control to keep rodent
numbers to a minimum. Maintain permanent bait stations or traps to control invading rodents
and to keep surviving rodents from multiplying.
Reference to products in this publication is not intended to be an endorsement to the exclusion of others which may be similar. Persons using such products assume responsibility for their use in accordance
with current directions of the manufacturer. The information represented herein is believed to be accurate but is in no way guaranteed. The authors, reviewers, and publishers assume no liability in connection with any use for the products discussed and make no warranty, expressed or implied, in that respect, nor can it be assumed that all safety measures are indicated herein or that additional measures may
be required. The user therefore, must assume full responsibility, both as to persons and as to property, for the use of these materials including any which might be covered by patent.
This material may be available in alternative formats.
PAGE PIG 04-04-04